Iommi formed part of the generation of artists who introduced avant-garde in Latin America. In 1946 he was a founder of the Arte Concreto-Invención group, which aesthetic concern was exclusively with the forms, shapes and colours, dissociated from any sort of figuration or representation of reality. His works of this period were executed in stainless steel, aluminium, wood, bronze and acrylics. From 1977 he radically changed his style, producing assemblages and installations as a way of making a criticism to the country's government, the Military junta.
After 2001 Iommi shifted towards a style free of complexities and produced works of a humoristic nature, by finding new functions and uses for everyday objects.